Since, I'm failing to upload an image via the GitHub system, I'm linking to an external screenshot:
http://freeimagehosting.nl/site2/image.php?di=QTMR
Bitcoin: v0.8.1-beta Qt: 4.8.3
I've reported a different kind of "assertion failed" error some months earlier, but this one seems unrelated.
It occurred once, upon starting Bitcoin-Qt in a Windows 7 environment. It has not reccurred since. Upon restarting, all appeared to work fine, and still does.